如何对字母大小写进行转换？

Question

具体是怎么实现的呢，我如何才能看见其源代码？

Answer 1

public String toUpperCase(Locale locale) {
        int     len        = count;
        int     off        = offset;
        char[]  val        = value;
        int     firstLower;        /* Now check if there are any characters that need changing. */
        scan: {
            char upperCaseChar;
            char c;
            for (firstLower = 0 ; firstLower < len ; firstLower++) {
                c = value[off+firstLower];
                upperCaseChar = Character.toUpperCaseEx(c);
                if (upperCaseChar == Character.CHAR_ERROR || c != upperCaseChar) {
                    break scan;
                }
            }
            return this;
        }        char[]  result       = new char[len]; /* might grow! */
int     resultOffset = 0;  /* result grows, so i+resultOffset
    * is the write location in result */ /* Just copy the first few upperCase characters. */
System.arraycopy(val, off, result, 0, firstLower);        if (locale.getLanguage().equals("tr")) {
            // special loop for Turkey
            char[] upperCharArray;
            char upperChar;
            char ch;            for (int i = firstLower; i < len; ++i) {
                ch = val[off+i];
                if (ch == 'i') {
                    result[i+resultOffset] = '\u0130';  // dotted cap i
                    continue;
                }
                if (ch == '\u0131') {                   // dotless i
                    result[i+resultOffset] = 'I';       // cap I
                    continue;
                }
                upperChar = Character.toUpperCaseEx(ch);
                if (upperChar == Character.CHAR_ERROR) {
                    upperCharArray = Character.toUpperCaseCharArray(ch);
                    /* Grow result. */
                    int mapLen = upperCharArray.length;
                    char[] result2 = new char[result.length + mapLen - 1];
                    System.arraycopy(result, 0, result2, 0,
                        i + 1 + resultOffset);
                    for (int x=0; x<mapLen; ++x) {
                        result2[i+resultOffset++] = upperCharArray[x];
                    }
                    --resultOffset;
                    result = result2;
                }
                else {
                    result[i+resultOffset] = upperChar;
                }
            }
        } else {
            // normal, fast loop
            char[] upperCharArray;
            char upperChar;
            char ch;
            for (int i = firstLower; i < len; ++i) {
                ch = val[off+i];
                upperChar = Character.toUpperCaseEx(ch);
                if (upperChar == Character.CHAR_ERROR) {
                    upperCharArray = Character.toUpperCaseCharArray(ch);
                    /* Grow result. */
                    int mapLen = upperCharArray.length;
                    char[] result2 = new char[result.length + mapLen - 1];
                    System.arraycopy(result, 0, result2, 0,
                        i + 1 + resultOffset);
                    for (int x=0; x<mapLen; ++x) {
                        result2[i+resultOffset++] = upperCharArray[x];
                    }
                    --resultOffset;
                    result = result2;
                }
                else {
                    result[i+resultOffset] = upperChar;
                }
            }
        }
        return new String(0, result.length, result);
    }